Field of the Invention
The invention relates to a sensor subassembly and to a method of producing the sensor subassembly. Such sensor subassemblies are used, in particular, in occupant protection systems of motor vehicles.
With the increasing use of electronic controllers and regulators, increasing importance is attached to the sensors. Sensor subassemblies containing sensors should be capable of cost-effective production and should supply precise, reliable output signals for the circuits connected downstream of the controller. Simple mounting of the sensor or of the sensor subassembly provided with the sensor is a further important requirement. When such sensor subassemblies are used in occupant protection systems of motor vehicles, it is usually the acceleration of an inertial mass contained in the sensor element which is measured or, in particular in side impact protection devices, a pressure wave is registered which, for example, originates from sudden deformation of an outer panel of a door.
Published, European Patent Application EP 0 297 961 A2 shows a sensor subassembly of the generic type whose sensor element responds to pressure. The sensor subassembly has a base part made of plastic, which is injection-molded around a punched grid. Sensor connections of a punched grid end within a sensor holding region formed by a hole in the base part. Towards one end, the base part is configured as a plug, from which ends of the punched grid project as plug connections. A sensor element is fastened to a supporting part that consists of plastic, which can be inserted into the hole-like sensor holding region and is electrically connected to the sensor connections, for example by use of a bonding. A further component, which engages over the sensor, is subsequently clipped to the base part. Overall the sensor subassembly is of relatively complicated construction. Before the evaluation of output signals from the sensor element which are picked off via the plug connections, a further device is needed for processing the signals in an EDP-suitable form, since signal processing directly on the sensor subassembly is not provided. Published, European Patent Application EP 0 566 758 A1 discloses a sensor subassembly whose sensor element is sensitive to acceleration. The sensor element is soldered to a printed circuit board by connecting legs and is additionally held on holding arms that are connected to the printed circuit board. The printed circuit board is disposed within a housing having insulating material which protects the sensor element from extremely hard impacts being disposed between the printed circuit board and the housing, and between the sensor element and the housing. The construction of this known sensor unit is also relatively complicated.